Esters of 4-cyclohexene-1, 2-dicarboxylic acid



Patented Sept. 18, 1945 ESTERS OF 4-GYCLOHEXENE-L2- DICARBOXYLIC ACID Clarence L. Moyle, Midland, Mich., assignor to The Dow Chemical Company, Midland, Mich., a corporation of Michigan No Drawing. Application October 1, 1941, Serial No. 413,123

9 Claims.

This invention concerns certain new esters and a method of making the same. The esters provided by the invention are haloalkyl and halocycloalkyl esters of 4-cyclohexene-1,2-dicarboxylic acid having the formula:

H AIR-C-O-Ih 'to the carboxyl group contains no halogen substituent. .They are colorless liquids or solids, soluhi in common organic solvents such as ethanol, methanol, carbontetrachloride and acetone-and are useful as agents for incorporation in vinylidene chloride polymers to stabilize the latter against decomposition by light and also as insecticidal ingredients of compositions, such as fly sprays, for the control of household insect pests.

The new esters may be prepared by reacting a halohydrin or a polyhaloalkanol in which the halogen atoms are attached to carbon atoms other than that connected with the hydroxyl group, which polyhaloalkanols are hereinafter included in the term halohydrin, with 4-cyclohexene-1,2- dicarboxylic acid or its anhydride. An esterification catalyst, e. g. benzene sulfonic acid and pphenol sulfonic acid, may be employed although this may not be necessary when the anhydride is reacted with a halohydrin to form a mono-ester. Mixed esters in which the two It groups in the formula given above represent different haloalhl or halocycloalkyl groups are preferably prepared by reacting the anhydride with one of the two corresponding halohydrins to form a monoester of e-cyclohexene-1,2-dicarboxylic acid and thereafter reacting the latter with the other halohydrin to form the mixed ester. The mixed esters 1 may also he formed by reacting the 4-cyclohexene-lz-dicarboxylic acid or its anhydride with a mixture or halohydrins.

fIhe reaction to form the ester may conveniently be carried out by heating a mixture of one or more halohydrins, e. g. ethylene chlorohydrin,

ethylene bromohydrin, propylene chlorohydrin,

propylene bromohydrin, butylene chlorohydrin, 1,3-dichloro-2-propanol, cyclohexene chloro ydrin, or methyl-cyclohexene chlorohydrin, etc., and 4-cyclohexene-1,2-dicarboxylic acid or its anhydride to boiling under reflux. The reactants maybe used in any desired proportions, but the yield of a mono-ester product is highest when 0.7 mol or more, preferably-about 1 mol, of it-cyclohexene-1,2-dicarboxylic acid or its anhydride is employed per mol of halohydrin. When a di-ester is desired, 2 mols-or more, preferably between 2 and 10 mols, of halohydrin may advantageously be used per mol of acid oranhydride reactant. The reaction is preferably carried out in the presence of an esterification catalyst, such as those hereinbefore mentioned, but a catalyst is not required. A very small proportion of catalyst, e. g. from 0.001 to 0.1 mol of catalyst per mol of the acid or anhydride reactant, usually sufllces-to promote smooth and rapid reaction.

When carrying out the reaction to form either p a monoor a di-ester using 4-cyclohexene-1,2- dicarboxylic acidas a reactant, and when carrying it out to form a di-ester using the corresponding acid anhydride as a reactant, water is, of course, formed as a, by-product. In such instances, the rate and completeness of the reaction may be furthered by removing the water as it is formed. This may be accomplished, by carrying the reaction out in the presence of a waterentraining agent such as benzene, toluene, ethylene chloride, or propylene chloride, etc., and dur- 4 ing the reaction distilling the entraining agent and water from the reaction mixture. In most instances, a portion of the halohydrin reactant may itself serve as such entraining agent for removal of the water. In the reaction of a halohydrin with an equimolecular amount of the acid anhydride to produce a mono-ester, water is not formed. From 1 to 3 hours of heating sufilces for carrying out the reaction, but longer heating may in some instances be required.

The ester products may be separated from the reacted mixture by usual purification procedures,

the preferred procedure depending, of course, upon whether it is a mono-ester, a di-ester, or a mixture thereof which has been produced. When, as is often the case, the reaction mixture contains both a mono-ester and a di-ester, it may conveniently be scrubbed with an aqueous solution of an alkali, e. g. NaOH, NazCOa, NaHCOa, or KHCOa, etc., to extract the acid ingredients including the mono-ester product and leave the diester. The latter may be further purified, if necessary, :by fractional distillation. The extract may then be acidified to precipitate the monoester which may be separated and further purij fled, e. 8. by crystallization from a solvent. Certain of such steps may, of course, be omitted wh n the t r pr duct to be separated from the crude reaction mixture is eithera mono-ester or a di-ester alone.

The following examples describe a number of ways in which the principle of the invention has been applied but are not to be construed as limiting the invention:

Example 1 93 grams (0.6 'mol) of 4-cyclohexene-1,2-dicarboxylic acid anhydrlde, 388 grams (4.83 mole) of anhydrous ethylene chlorohydrin and 1 gram (0.006 moi) of benzene sulfonic acid were heated together in a flask fitted with a. condenser. The excess chlorohydrin and the water formed during the reaction were slowly distilled over a period of two hours. The crude di-(2-chloroethyl) ester of -cyclohexene-1,2-dicarboxylic acid remaining in the flask was mixed with 150 c. 'c. of carbon tetrachloride and the mixtur washed free of acidic ingredients with dilute. aqueous sodium carbonate solution. It was then fractionaily distilled, whereby there was recovered 150.1 grams (0.505 mol) of the pure ester, or a yield of 84 per cent of theory based on the 4-cyc1ohexene-L2-dicarboxylic acid anh'ydridefiused. Dl-(2-chloroethyl) cyclohexene 1 ,2 dicarboxylate is a. colorless, mobile liquid-boiling at 185-190" C. under 7 mm. pressure. It is only slightly solu- Example 2 30.4 grams (0.2 mol) of 4-cyclohexene-L2-dicarboxylic acid anhydride and 16.1 .grams (0.2 mol) of anhydrous ethylen chiorohydrin were stirred together for four hours at 110-125 C. The crude reaction mixture was extracted with 220 grams of 10 per cent aqueous sodium bicarbonate solution. A small amount of insoluble material was separated from the aqueous extract and the latter was then acidified with hydrochloric acid, whereby there was obtained 32.

In a manner similar to that described in--Example 1, 4-cyclohexene-1,2-dicarboxylic acid anhydride was, in separate experiments, reacted with 1-chloropropanol-2, 1,3-dichloropropanol-2, and 3-chloropropanol-l, respectively, to form the corresponding di-haioalkyl esters. The reaction bl in water. Its specific gravity is 1.25 at 25 conditions for the formation of these di-esters Table M018 M018 Reaction conditions Dlhaloalkylester products anh Halohyadrln balm I use Time Press. Temp. M. P. 3.1 D;i N3 Formula Ham 11 5 25 wl" l78 1%8 t 1 1s 1 4837 H lat l cons a a 2 31 59 20 3 0 m liquid. 5.5 mm. c cum no CH-lJ-W- HCH; ark cH-c-o-c11cm c 0 H101 Ha o 1 tm 160-172 do 230-240 at 1.32 1.5103 H, 'zgl gi f 2o a 5.0mm. c 0 0mm HO cn-c-o-cncmcl 3 Hc-o-cHcH,c1

0.3 3-chloropropa- 1.8 3.0 125-140 mm. -135 74.5-76 (1) 1g, 0

no-l.

I no cn-c-o-cmcmcmcl H n-c-o-cmcmcmcl c Ha 1 Crude product washed with dilute sodium hydroxide and recrystallized from ethanol.

C. referred to water at 25 C. and its refractive and their properties are given in the accompanyindex, N is 1.4933. It has the formula:

cn-c-o-cnicmcl ing table.

Among the mono-haloallryi and-mono-ha'iocycloalkyl esters of 4-cyclohexene-1,2-dicarboxylic acid which may be prepared by reacting 4-cyclohexene-1,2-dicarboxylic acid or its anhydride with the appropriate halohydrin or halocyclohexanol are the l-chloro-Z-Propyl, 3-chloro'= ethyl) ester with 3-chloropropanol-1, and the 2-.

bromoethyl 2,2'-dichloroisopropyl ester prepared by reacting the mono-(2,2'-dichloroisopropyl) ester with 2-bromoethanol-1. Other di-haloalkyl and .di-halocycloalkyl esters in addition to those listed in the above examples which may be prepared by heating. 4-cyclohexene-L2-dicarboxylic acid or its anhydride with the appropriate halohydrin or halocyclohexanol are the (ii-(2Q bromoethyl) the di-( 2-bromoisopropy1) and the di-(z-chlorocyclohexyl) esters.

Other modes of applying the principle of the invention may be employed instead of those explained, change being. made as regards the materials employed provided the products described in the following claims be obtained.

I, therefore, particularly point out tinctly claim as my invention:

1. A compound having the formula:

H: o c (JR-'A-O-R n-o-o-n.

wherein R represents a memberof the consisting of haloalkyl and halocycloalkyl radicals, which radicals contain a plurality of carbon atoms and in which the carbon .atom attached to the carboxyl group contains no halogen substituent and R1 represents a member of th group consisting of hydrogen and of haloalkyl and halocycloalkyl radicals, which radicals contain a plurality of carbon atoms and in which the carbon atom attached to the carboxyl group contains no halogen substituent,

2. A compound having the formula:

and dis- 3 w consisting of haloalkyl and halocycloalkyl radicals, which radicals contain a plurality of carbon atoms and in which the carbon atom attached to the carboxyl group contains no halogen substituent;

3. A compound having the form Hg C\ .HC CH-'J-O-CHr-CdHr-q-J- n nco--cmc.m.+.-.x.

wherein n and m are integers and mis less than 2n+2 and x represents a member of the class consisting of bromine, and chlorine.

4. Acompound having the formula:

wherein n and m are integers and m is less than 2n+2 and represents a member of the class consisting of bromine and chlorine.

5. A compound having the formula:

no CH'50-OHr-C-H: 1--Cl- 'n-c-o-c-m-cmm-mn c HI I wherein'n and m are integers and m is less than 2n+2.

6. A compound having the formula:

HI Y C 0 i no crre- -o-onr-mhmucl.

wherein n and m are integers and m is less than 2n+2.

7. The mono-(z-chloro'ethyl) ester of 4-cyclohexene-lz-dicarboxylic acid.

8. The di-(z-chloroethyl) ester of -cyclohexene-ifl-dicarboxylic acid.

9. The di-(1-chloro-2.-propyl) ester of 4-cyclohexene-1,2-dicarboxylic acid.

. CLARENCE L. MOYIE'.

wherein R represents a member of the group 

